Systems for spinal stabilization

ABSTRACT

Systems, devices and methods related to spinal stabilization are provided. A system can comprise a plurality of cross-links. Each of the cross-links can include a central rod holder that extends substantially along a mid-line of the spine and a pair of extension members extending from the central rod holder. The extension members can be secured to a vertebral body via a fixation device, such as a spinal screw or a hook member having serrations and/or side-cuts. One or more rod members can be extended across the central rod holders of the cross-links, thereby forming a stable spinal stabilization system providing bilateral stress distribution across different levels of the spine.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/012,882, filed on Feb. 2, 2016 (published as U.S. Pat. Pub. No.2016-0151095), which is a continuation of U.S. patent application Ser.No. 13/352,583, filed Jan. 18, 2012 (now U.S. Pat. No. 9,283,001), allof which are incorporated herein by reference in their entireties forall purposes.

FIELD OF THE INVENTION

The present application is generally directed to orthopedicstabilization systems, and in particular, to central stabilizationsystems including rod members and fixation members.

BACKGROUND OF THE INVENTION

Many types of spinal irregularities cause pain, limit range of motion,or injure the nervous system within the spinal column. Theseirregularities can result from, without limitations, trauma, tumor, discdegeneration, and disease. Often, these irregularities are treated byimmobilizing a portion of the spine. This treatment typically involvesaffixing a plurality of screws and/or hooks to one or more vertebrae andconnecting the screws or hooks to an elongate rod that generally extendsin the direction of the axis of the spine.

Treatment of these spinal irregularities can involve using a system ofscrews and rods to attain stability between spinal segments. Instabilityin the spine can create stress and strain on neurological elements, suchas the spinal cord and nerve rods. In order to correct this, implants ofcertain stiffness can be implanted to restore the correct alignment andportion of the vertebral bodies. In many cases, these implants can helprestore spinal elements to a pain free situation, or at least may helpreduce pain or prevent further injury to the spine.

Accordingly, there is a need for improved systems involving screws androds for spinal stabilization.

SUMMARY OF THE INVENTION

Various systems, devices and methods related to spinal stabilization areprovided. In some embodiments, a method for spinal stabilizationcomprises providing a plurality of cross-links, each of the cross-linksincluding a central rod holder and first and second extension membersextending therefrom. Each of the cross-links can be operably attached toa vertebral body by attaching a first extension member to a firstfixation member and attaching a second extension member to a secondfixation member. The first fixation member and the second fixationmember can be attached to the vertebral body. Once two or morecross-links are installed, a rod member can be secured to the centralrod holders of the multiple cross-links, thereby creating a stabilizedsystem across multiple levels of the spine.

In some embodiments, a method for spinal stabilization comprisesproviding one or more cross-links configured to extend across a mid-lineof a spine. A first portion of a cross-link can be attached to a firstfixation member, wherein the first fixation member is attached to avertebral body. A second portion of the cross-link can be attached to asecond fixation member, wherein the second fixation member is attachedto a vertebral body. At least one of the first fixation member and thesecond fixation member is a hook member having a pair of arms and amouth with serrations.

In some embodiments, a method for spinal stabilization comprisesproviding one or more cross-links configured to extend across a mid-lineof a spine. A first portion of a cross-link can be attached to a firstfixation member, wherein the first fixation member is attached to avertebral body. A second portion of the cross-link can be attached to asecond fixation member, wherein the second fixation member is attachedto a vertebral body. At least one of the first fixation member and thesecond fixation member is a hook member having a pair of arms forming achannel, wherein at least one of the arms includes a side-cut formedtherein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood with reference to theembodiments thereof illustrated in the attached figures, in which:

FIG. 1 is a top view of a central rod system in use according to someembodiments.

FIG. 2 is a top view of a central rod system according to someembodiments.

FIG. 3 is a front view of a cross-link of a central rod system accordingto some embodiments.

FIG. 4 is a top perspective view of a cross-link of a central rod systemaccording to some embodiments.

FIG. 5 is a front view of a cross-link of a central rod system having arod therein according to some embodiments.

FIG. 6A is top view of a cross-link of a central rod system attached toa vertebral body according to some embodiments.

FIG. 6B is a front view of a cross-link of a central rod system attachedto a vertebral body according to some embodiments.

FIG. 7 is a perspective view of a hook member having serrationsaccording to some embodiments.

FIG. 8 is a side view of a hook member having serrations according tosome embodiments.

FIG. 9 is a perspective view of a hook member having side-cuts accordingto some embodiments.

FIG. 10 is a perspective view of a hook member having alternativeside-cuts according to some embodiments.

FIG. 11 is a perspective view of a hook member having alternativeside-cuts according to some embodiments.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Embodiments of the invention will now be described. The followingdetailed description of the invention is not intended to be illustrativeof all embodiments. In describing embodiments of the present invention,specific terminology is employed for the sake of clarity. However, theinvention is not intended to be limited to the specific terminology soselected. It is to be understood that each specific element includes alltechnical equivalents that operate in a similar manner to accomplish asimilar purpose.

The present application is generally directed to orthopedicstabilization systems, and in particular, to central stabilizationsystems including rod members and fixation members.

FIG. 1 is a top view of a central rod system in use with a spineaccording to some embodiments. The central rod system 10 comprises aplurality of cross-links 20 that extend along different spinal levels.Each of the cross-links in the system (shown individually in FIGS. 3 and4), advantageously include a central rod holder 25 that is designed tohold one or more rod members across multiple spinal levels. As shown inFIG. 1, one or more central rods 50 can extend through the central rodholders 25 of the cross-links 20, thereby helping to create a stablesystem to ease complex deformity correction. In some embodiments, thecentral rods 50 extend over reduced or removed spinal processes suchthat they are positioned substantially through a center of the spine.

Each of the central rod holders 25 also includes a pair of extensionmembers 27, 28 that extend outwardly from the central rod holder 25.Each of the extension members 27, 28 can be attached to a fixationelement, such as such as a screw. As shown in FIG. 1, extension member27 is attached to fixation element 70, while extension member 28 isattached to fixation element 80. The fixation elements 70, 80advantageously help to secure the extension members 27, 28 of thecentral rod holder 25 bilaterally on opposite sides of a mid-line of thespine. More details with respect to the central rod holder 25 arediscussed below.

FIG. 2 is a top view of a central rod system according to someembodiments. The central rod system 10 includes seven cross-links 20,each having a central rod holder 25 and a pair of extension members 27,28 extending outwardly therefrom. In some embodiments, differentextension members 27, 28 in a central rod system can have differentlengths to advantageously accommodate different levels of the spine. Forexample, as shown in FIGS. 1 and 2, extension members 27, 28 found on ahigher portion of the spine (e.g., in the lumbar region) can be shorterin length than extension members found in a lower portion of the spine(e.g., the sacrum). In some embodiments, the central rod system includeextension members 27, 28 that increase in length from a higher portionto a lower portion of the spine.

FIG. 3 is a front view of a cross-link of a central rod system accordingto some embodiments. As noted above, the cross-link 20 includes acentral rod holder 25 with a pair of extension members 27, 28 extendingtherefrom. In some embodiments, the central rod holder 25 comprises anopen or closed connector head that can be offered in a variety ofconfigurations, including but not limited to, a monoaxial head,uniplanar head, polyaxial head, spinning head and a sliding head.

The central rod holder 25 comprises a pair of arms 31, 32 that formsidewalls of a U-shaped channel 35. In some embodiments, the arms 31, 32each include recessed portions 33, 34, which can be engaged by aninsertion instrument or sleeve to deliver the cross-link to a desiredlocation adjacent a spine. The U-shaped channel 35 is configured toreceive one or more rod members that connect across multiple levels ofthe spine to provide spine stabilization.

FIG. 4 is a top perspective view of a cross-link of a central rod systemaccording to some embodiments. From this view, more details of the arms31, 32 of the central rod holder 25 are visible. The arms 31, 32 eachinclude individual apertures 37, 38. In some embodiments, the individualapertures 37, 38 can receive a part of an insertion instrument orsleeve, such as a tab member, to assist in securing the instrument tothe arms during delivery of the cross-link.

FIG. 5 is a front view of a cross-link of a central rod system having arod therein according to some embodiments. The rod 50 is positionedwithin the central rod holder 25 of the cross-link 20.

In addition, the extension members 27, 28 of the cross-link areoperatively attached to fixation members 70, 80. Each of the fixationmembers 70, 80 includes a head member 72, 74 for receiving extensionmembers 27, 28 therein. The head members 72, 74 are connected to shafts75, 85 that can be inserted into the spine for fixation.

Methods related to the central rod systems discussed above are nowprovided. In some embodiments, a surgical procedure for installing acentral rod system involves removing all or a portion of one or morespinal processes. In other embodiments, the spinal processes remainintact while components of a central rod system curve or work around thespinal processes. In some embodiments, once the spinal processes areremoved, a plurality of cross-links are provided. Each of thecross-links includes a central rod holder and first and second extensionmembers extending therefrom. The cross-links can be installedindividually to a vertebral body by securing the first extension memberto the vertebral body via a first fixation member (e.g., a screw or ahook) and by securing the second extension member to the vertebral bodyvia a second fixation member (e.g., a screw or a hook). Lockingmechanisms, such as locking caps, can be provided to secure theextension members to the fixation members.

FIGS. 6A and 6B illustrate a single cross-link member 20 attached to avertebral body 5. The cross-link member 20 has a central rod holder 25and extension members 27, 28 extending therefrom that are secured to avertebral body via fixation members 70, 80. From the view in FIG. 6B,one can see how the cross-link member 20 is attached over a modifiedspinous process 8. One or more cross-link members can be attached asshown in these figures.

During surgery, one or more cross-links can be installed such that theircentral rod holders align substantially along a mid-plane of the spineand/or over the modified spinal processes. After installing a pluralityof cross-links, one or more rod members can be inserted through thecentral rod holders and secured therein (e.g., via a locking mechanismor cap). The one or more rod members extend across multiple levels ofthe spine, thereby creating a stable, central rod system across multiplelevels.

By providing a central rod system as discussed above, a number ofadvantages are achieved for spinal stabilization. Among the advantagesinclude bilateral stress distribution to alleviate unilateral stressconcentrations during deformity correction; centralized sagital plantcorrection; reduced rod bending in planar operations (e.g., lordosis andkyphosis); a centralized rotation axis allowing for a more intuitivelocal vertebral rotation; and a system that can be utilized toaccommodate growing rod applications.

In addition or instead of the components of the central rod systemdiscussed above, other components can be used. For example, a variety ofdifferent hook members can be used instead of the pedicle screws 70, 80shown above for attachment to a vertebral body. While such hook memberscan be used as part of a central rod system as discussed above, they canalso be used in other spine systems that are different from the centralrod system. Novel hook members are discussed below.

FIG. 7 is a perspective view of a hook member having serrationsaccording to some embodiments. The hook member 100 includes a pair ofarms 131, 132 that form a channel 135 for receiving a rod membertherein. The arms can include one or more apertures 138 formed thereon,which can be grasped by an insertion or delivery instrument. The bottomof the channel 135 can sweep downwardly to form a mouth 140. The mouth140 of the hook member 100 can advantageously be used to grasp a bonemember. Advantageously, the serrations 142 provide the hook member 100with additional fixation in both translational and rotational planessuch that the likelihood of back out or migration of the hooks isreduced.

In some embodiments, the mouth 140 of the hook member 100 includes aplurality of serrations 142 thereon. The serrations 142 advantageouslyprovide multiple points of contact that dig into bone when the hookmember 100 is press-fitted onto bone.

FIG. 8 is a side view of a hook member having serrations according tosome embodiments. From this view, the geometry of the serrations 142 canbe seen. As shown in FIG. 8, the serrations 142 can be evenly spaced,and can resemble triangular or pyramidal teeth. In other embodiments,the hook member 100 can include serrations or frictionalcontact-surfaces with other shapes, including saw-tooth forms, ridgesand rounded bumps.

FIG. 9 is a perspective view of an alternative hook member that can beused alone or in combination with a spinal system, such as the centralrod system discussed above. Like the hook member 100 in FIG. 8, the hookmember in FIG. 9 includes a pair of arms 131, 132 that form a channel135 for receiving a rod member therein, as well as a mouth portion 140for attachment to a vertebral body. The arms 131, 132 can include one ormore apertures 138 for gripping by an insertion instrument.Advantageously, the arms 131, 132 of the hook member 100 can alsoinclude side-cuts 139. These side-cuts advantageously provide additionalpoints of contact with respect to instruments that hold it while thehook is press-fitted into bone. In other words, the hook member 100 hasadditional fixation points for the instrument to engage with, in bothtranslational and rotational planes, thereby reducing the chance of hookslippage during implantation.

FIGS. 9-11 each show hook members 100 having side-cuts 139 withdifferent shapes and geometries. In FIG. 9, the hook member 100 includesa side-cut 139 a that is rounded and appears as a semi-circle. In FIG.10, the hook member 100 includes a side-cut 139 b that appears as arectangular recess formed in the arms 131, 132 of the hook member 100.In FIG. 11, the hook member 100 includes a side-cut 139 that iscompletely rectangular cut-out and not simply a recess. Accordingly, thehook members 100 have a number of differently shaped and orientedside-cuts that be gripped by an insertion instrument.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations can be made thereto by those skilled in the art withoutdeparting from the scope of the invention.

What is claimed is:
 1. A spinal stabilization system comprising: firstand second cross-links, each of the cross-links including a central rodholder and first and second extension members extending therefrom,wherein the first and second extension members have a generally arcuatelower portion and a generally planar upper portion; a first fixationmember, wherein the first fixation member is configured to be attachableto a first vertebra via a shaft portion, wherein the first fixationmember comprises a pair of upwardly extending arms for receiving thefirst extension member of the first cross-link therein; a secondfixation member, wherein the second fixation member is configured to beattachable to the first vertebra via a shaft portion, wherein the secondfixation member comprises a pair of upwardly extending arms forreceiving the second extension member of the first cross-link therein; athird fixation member, wherein the third fixation member is configuredto be attachable to a second vertebra via a shaft portion, wherein thethird fixation member comprises a pair of upwardly extending arms forreceiving the first extension member of the second cross-link therein; afourth fixation member, wherein the fourth fixation member is configuredto be attachable to the second vertebra via a shaft portion, wherein thefourth fixation member comprises a pair of upwardly extending arms forreceiving the second extension member of the second cross-link therein;and a rod member, wherein the rod member is received in the central rodholder of the first and second cross-links thereby creating a stabilizedsystem across multiple levels of the spine.
 2. The system of claim 1,wherein the first and second extension members are solid without anyopenings.
 3. The system of claim 1, wherein a width of the extensionmembers of the first cross-link is different from a width of theextension members of the second cross-link.
 4. The system of claim 1,further comprising a third, fourth and fifth cross-link.
 5. The systemof claim 4, wherein at least one of the cross-links is configured toattach to a sacrum.
 6. The system of claim 1, wherein the first fixationmember is configured to be attachable to a pedicle of the firstvertebra.
 7. The system of claim 6, wherein the second fixation memberis configured to be attachable to a pedicle of the first vertebra. 8.The system of claim 2, wherein the first fixation member furthercomprises a side cut, wherein the side cut also opens into the channelformed by the pair of upwardly extending arms.
 9. The system of claim 1,wherein the central rod holder comprises a pair of upwardly extendingarms forming a channel therein, wherein the first and second extensionmembers extend outwardly from the pair of upwardly extending arms. 10.The system of claim 9, wherein the pair of upwardly extending arms formssidewalls of the channel and each arm includes a recessed portionconfigured to be engaged by an insertion instrument.
 11. A spinalstabilization system comprising: first and second cross-links, each ofthe cross-links including a central rod holder and first and secondextension members extending therefrom; a first fixation member, whereinthe first fixation member is configured to be attachable to a firstvertebra via a shaft portion, wherein the first fixation membercomprises a pair of upwardly extending arms for receiving the firstextension member of the first cross-link therein; a second fixationmember, wherein the second fixation member is configured to beattachable to the first vertebra via a shaft portion, wherein the secondfixation member comprises a pair of upwardly extending arms forreceiving the second extension member of the first cross-link therein; athird fixation member, wherein the third fixation member is configuredto be attachable to a second vertebra via a shaft portion, wherein thethird fixation member comprises a pair of upwardly extending arms forreceiving the first extension member of the second cross-link therein; afourth fixation member, wherein the fourth fixation member is configuredto be attachable to the second vertebra via a shaft portion, wherein thefourth fixation member comprises a pair of upwardly extending arms forreceiving the second extension member of the second cross-link therein;and a rod member, wherein the rod member is received in the central rodholder of the first and second cross-links thereby creating a stabilizedsystem across multiple levels of the spine, wherein each of the pair ofupwardly extending arms include recessed portion that are configured toengage with an insertion instrument, and wherein the aperture of each ofthe pair of upwardly extending arms are positioned in the recessedportions of the upwardly extending arms.
 12. The system of claim 11,wherein the first and second extension members are solid without anyopenings.
 13. The system of claim 11, wherein a width of the extensionmembers of the first cross-link is different from a width of theextension members of the second cross-link.
 14. The system of claim 11,further comprising a third, fourth and fifth cross-link.
 15. The systemof claim 14, wherein at least one of the cross-links is configured toattach to a sacrum.
 16. The system of claim 11, wherein the firstfixation member is configured to be attachable to a pedicle of the firstvertebra.
 17. The system of claim 16, wherein the second fixation memberis configured to be attachable to a pedicle of the first vertebra. 18.The system of claim 12, wherein the first fixation member furthercomprises a side cut, wherein the side cut also opens into the channelformed by the pair of upwardly extending arms.
 19. The system of claim11, wherein the central rod holder comprises a pair of upwardlyextending arms forming a channel therein, wherein the first and secondextension members extend outwardly from the pair of upwardly extendingarms.
 20. The system of claim 19, wherein the pair of upwardly extendingarms forms sidewalls of the channel.